“Observations have shown that nearly every galaxy has a supermassive black hole — a black hole with a mass of one million to one billion times that of the sun — at its center and that galaxies often collide and merge to create larger galaxies. Astronomers have expected to find many mid-merge galaxies by focusing on the two supermassive black holes, which should be orbiting each other in the middle.”

Now, innovative observational techniques have identified 33 of the ‘waltzing’ black hole pairs. (Wired News)